High speed composite system



Nov. 1o, 1936. P. J. HOWE ET AL 2,060,574

HIGH SPEED COMPOSITE SYSTEM ,Paul Jowe aberi' Zjazleii MauriceA. RuddNov. 10, 1936. p, L HOWE ET AL 2,060,574

HIGH SPEED COMPOSITE SYSTEM A Filed July 8, 1935 2 Sheets-Sheet 2 file ZPatented Nov. 10, 1936 UNITED STATES PATENT OFFICE HIGH SPEED COMPOSITESYSTEM Application July 8, 1935, Serial No. 30,388

12 Claims.

This invention relates to signaling systems embodying a plurality ofsimplex, duplex or multiplex telegraph circuits and a compositedtelephone circuit and more particularly to composite sets associatedwith the` terminal facilities of the lines of such systems to preventthe different currents in the lines from interfering with each other.

In a signaling system in which both telegraph and telephone currents aretransmitted over the line circuits, it has been the practice toassociate with the terminal facilities of such line circuits, anarrangement known as a composite set for separating and diverting theincoming telegraph and telephone currents to their respective circuitswithout interference with each other. The composite apparatus alsofunctions to prevent the outgoing telegraph currents from entering thetelephone path at the terminal facilities and vice versa.

The successful operation of a composited circuit depends upon: (l) Theremoval from the telegraph signals of the higher frequency components,which would introduce noise into the telephone, while retainingsuiiicient of the signaling components to avoid affecting the properoperation of the telegraph circuit; (2) the prevention of the passage ofany of the telephone signals into the telegraph apparatus; (3)connection of the telephone circuit between the two line wires in such away that telephone signals may pass easily into the telephone apparatuswhile the passage of telegraph signals is prevented.

While the perfect accomplishment of the abovenamed requirements cannotbe attained in practice, the object of the present invention is toprovide an improved composite system for modern high speed signalingsystems wherein the disturbing elements are reduced or eliminated tosuch an extent that satisfactory telephone circuits are obtained withoutserious loss to the telegraph circuits.

Our invention will be more fully understood from the followingdescription in connection with the accompanying drawings in which-Figure 1 is a diagrammatic illustration of a pair of duplexed telegraphlines and a telephone composited therewith in accordance with ourinvention;

Figure 2 is a similar circuit diagram embodying a modification of theneutralizing arrangement of the composite apparatus; and

Figures 3 and 4 are diagrammatic views showing our invention applied tosimplex lines.

Referring to Fig. 1 each of the duplex lines is provided with a filteror anti-noise set 3, in the apex 'lead connecting the transmitter 2 tothe main line relay 4. As is known, this arrangement shunts a portion ofthe Voice frequency components of the telegraph signals to ground.However, as the telegraph signals traverse the coils of the main linerelay, voice frequency components are again added to the outgoingsignals, these being generated by the movements of the relay tongue inthe magnetic field of the relay.

For the purpose of eliminating the undesirable signal components in thetelegraph signals after they pass from the main line relay coils we havedevised the high speed composite set or apparatus which is located atthe terminal switchboard.

This embodies a line filter comprising the inductf ance of thetransformer 6, the shunt condenser 'l and the resistance 8. 'I'he linefilter causes a certain portion of the undesirable signal components tobe shunted to ground. It also prevents the passage of the telephonesignals into the telegraph set. The efficiency of the line filter isgreatly enhanced by grounding the condenser through a resistance 8.

In order to further decrease and eliminate undesirable components fromthe telegraph signals, We associate with the line filter a neutralizingcircuit as a part of the composite set. As the telegraph signals and theremaining voice frequency components traverse the primary coil of theline filter 6, currents are thereby induced in the secondary coil whichpass through a coil of the telephone coupler I0 to ground. Since theundesirable voice frequency components of the signals which traversedthe primary coil also flow through the coupler l0 to ground, it isevident that these two currents can be made to practically neutralizeeach other. For the purpose of bringing these currents into opposingphase relation, we provide a shaping circuit I2. In this manner, we areenabled to so far eliminate the undesirable voicefrequency componentsfrom the signals that objectionable noises are not heard in thetelephones and a satisfactory service is obtained.

The telephone circuit is obtained by bridging the telephone couplingcircuit across the two telegraph lines as indicated. The couplingcircuit through its condensers I4 provides an easy path for thetelephone (Voice frequency) currents but greatly restricts any passageof telegraph (low frequency) currents.

The lineman may bridge his portable telephone set to the composited lineconductors at any time without fear of interrupting the normal telegraphcircuits working over the wires, proM vided, of course, that he does notground or short circuit the line wires. When the lineman desires to calla terminal station, he clips his telephone set cords to the two lineconductors and then signals the desired station either with his voice orwith his voice frequency buzzer.

In order that satisfactory duplex balances may be obtained on thetelegraph circuits, it is necessary to compensate for the line filterwhich has been connected in the telegraph circuit. We, therefore, embodyin the composite apparatus a filter compensating network I5, comprisingcondenser, inductance and resistance, and connect it in shunt to theartificial line. rl'he constants of this shunt filter-compensatingnetwork are so designed that they closely approximate the impedance (attelegraph frequencies) of the filter network in series with the lineconnection of the telegraph set.

In order that ordinary duplex lines may be readily changed and embodiedin a composite system, the compensating network I5 is located at theterminal switchboard and is connected by conductor I6 to the head of theartificial line AL.

Figure 2 discloses another arrangement embodying our invention. In thisarrangement the neutralizing circuit associated with the line filter isinductively connected to the telephone coupler I0 by means of the coilsof a transformer 61. It is evident that the resultant effect ofneutralizing the voice frequency components of the signals is the sameas in the arrangement disclosed in Fig. 1.

Our invention may be applied to a simplex telegraph circuit in the samemanner as above described for duplex lines. The arrangementscorresponding to Figs. l and 2 are illustrated in Figs. 3 and 4 and theywill be understood from the previous description.

While our high speed composite system has been disclosed as embodied incertain specific arrangements which are deemed desirable, it isunderstood that it is capable of embodiment in other forms as covered bythe appended claims.

We claim as our invention:-

1. In a composite signaling system, a pair of duplexed telegraph lines,a bridge circuit connected between said lines and including condensersand intermediate inductances having a central ground connection,telephone apparatus connected to said bridge circuit at pointsintermediate said condensers and impedances, and composite apparatus foreliminating the voice frequency components of the telegraph signalstransmitted over said lines, comprising a line filter in each linehaving a grounded condenser and means inductively connecting said linefilter with said bridge circuit and embodying a shaping network adaptedto adjust the voice frequency currents flowing therein into oppositephase relation with the voice frequency components of the outgoingsignal currents flowing into the bridge circuit from the line.

2. A composite signaling system as set forth in claim 1 and afilter-compensating network con-- nected in shunt to the artificial lineof each duplexed line, embodying condenser and other impedance elementscorresponding to the elements in the line filter.

3. In a composite signaling system, a pair of duplexed telegraph lines,a bridge circuit connected between said lines and including condensersand intermediate inductances having a central ground connection,telephone apparatus connected to said bridge circuit at pointsintermediate said condensers and. impedances, and

composite apparatus for eliminating the voice frequency components ofthe telegraph signals transmitted over said lines, comprising a linefilter in each line having a grounded condenser and means inductivelyconnecting said line filter with said bridge circuit and a resistanceelement interposed in a connection between said condenser and ground.

4. In a composite signaling system, a pair of duplexed telegraph lines,a bridge circuit connected between said lines and including condensersand intermediate inductances having a central ground connection,telephone apparatus connected to said bridge circuit at pointsintermediate said condensers and impedances, and composite apparatus foreliminating the voice frequency components of the telegraph signalstransmitted over said lines, comprising a line filter in each linehaving a grounded condenser and means inductively connecting said linefilter with said bridge circuit, embodying a shaping network adapted toadjust the voice frequency currents flowing therein into opposite phaserelation with the voice frequency components of the outgoing signalcurrents flowing into the bridge circuit from the line, and afilter-compensating network connected in shunt to the artificial line ofeach duplexed line, embodying condenser and impedance elementscorresponding to the elements in the line filter, said compensatingnetwork being connected to the head end of the artificial line, wherebyany duplexed line may be connected in a composite system at the terminalswitchboard.

5. In a composite signaling system, a pair of duplexed telegraph lines,a bridge circuit connected between said lines and including condensersand intermediate inductances having a central ground connection,telephone apparatus connected to said bridge circuit at pointsintermediate said condensers and inductances, and composite apparatusfor eliminating the voice frequency components of the telegraph signalstransmitted over said lines, comprising a line filter in each linehaving a grounded condenser and means inductively connecting said linelter with said bridge circuit, comprising a transformer' having itslprimary coil in the line and its secondary connected to said bridge anda shaping network grounded at one end and connected in series with saidsecondary coil, operating to adjust the voice frequency currents inducedin said coil into opposite phase relation with the voice frequencycomponents of the outgoing signal currents flowing into the bridgecircuit from the line.

6. In a composite signaling system, a pair of duplexed telegraph lines,a bridge circuit connected between said lines and including condensersand intermediate coils constituting transformer primaries and groundedtherebetween, telephone apparatus connected to said bridge circuit atpoints intermediate said condensers and primaries, and compositeapparatus for eliminating the voice frequency components of thetelegraph signals transmitted over said lines, comprising a line filterin each line provided with a grounded condenser, and means inductivelyconnecting said line filter with said bridge circuit, comprising aconductor connected at one end to said line filter and at the other endto the free end of a secondary coil of said transformer, and a shapingnetwork connected in series with said conductor intermediate said filterand said secondary coil.

7. In a composite signaling system, a pair of duplexed telegraph lines,a bridge circuit connected between said lines and including condensersand intermediate coils constituting transformer primaries and groundedtherebetween, telephone apparatus connected to said bridge circuit atpoints intermediate said condensers and primaries, and compositeapparatus for eliminating the voice frequency components of thetelegraph signals transmitted over said lines, comprising a line filterin each line provided with a grounded condenser, and means inductivelyconnecting said line filter with said bridge circuit, comprising aconductor connected at one end to said line lter and at the other end tothe free end of a secondary coil of said transformer, a shaping networkconnected in series with said conductor intermediate said filter andsaid secondary coil, and a filter compensating network connected incircuit with the articial line.

8. In a composite signaling system, a pair of telegraph lines, a bridgecircuit connected between said lines and including condensers andintermediate inductances having a central ground connection, telephoneapparatus connected to said bridge circuit at points intermediate saidcondensers and inductances, and composite apparatus for eliminating thevoice frequency components of the telegraph signals transmitted oversaid lines, comprising a line lter in each line having a groundedcondenser and means'inductively connecting said line filter with saidbridge circuit and embodying a shaping network adapted to adjust thevoice frequency currents flowing therein into opposite phase relationwith the voice frequency components of the outgoing telegraph currentsiiowing to the bridge circuit from the line.

9. In a composite signaling system, a pair of telegraph lines, a bridgecircuit connected between said lines and including condensers andintermediate inductances having a central ground connection, telephoneapparatus connected to said bridge circuit at points intermediate saidcondensers and inductances, and composite apparatus for eliminating thevoice frequency cornponents of the telegraph signals transmitted oversaid lines, comprising a line filter in each line having a groundedcondenser, a resistance element interposed in the connection betweensaid condenser and ground, and means inductively connecting said linefilter with said bridge circuit.

10. In a composite signaling system, a pair of telegraph lines, a bridgecircuit connected between said lines and including condensers andintermediate inductances having a central ground connection, telephoneapparatus connected to said bridge circuit at points intermediate saidcondensers and inductances, and composite apparatus for eliminating thevoice frequency components of the telegraph signals transmitted oversaid lines, comprising a line filter in each line having a groundedcondenser and means inductively connecting said line lter with saidbridge circuit, embodying a shaping network adapted to adjust the voicefrequency currents flowing therein into opposite phase relation with thevoice frequency components of the outgoing telegraph currents flowinginto the bridge circuit from the line.

1l. In a composite signaling system, a pair of telegraph lines, a bridgecircuit connected between said lines and including condensers andintermediate inductances having a central ground connection, telephoneapparatus connected to said bridge circuit at points intermediate saidcondensers and inductances, and cornposite apparatus for eliminating theVoice frequency components of the telegraph signals transmitted oversaid lines, comprising a line lter in each line having a groundedcondenser and means inductively connecting said line filter with saidbridge circuit, comprising a shaping network and a transformer havingits primary coil in the line and its secondary connected in series withsaid shaping network, said network operating to adjust the voicefrequency currents induced in said coil into opposite phase relationwith the voice frequency components of the outgoing telegraph circuitsflowing into the bridge circuit from the line.

12. In a composite signaling system, a pair of telegraph lines, a bridgecircuit connected between said lines and including condensers andintermediate coils constituting transformer primaries and groundedtherebetween, telephone apparatus connected to said bridge circuit atpoints intermediate said condensers and primaries and compositeapparatus for eliminating the voice frequency components of thetelegraph signals transmitted over said lines, comprising a line filterin each line provided with a grounded condenser, and means inductivelyconnecting said line filter with said bridge circuit, comprising aconductor connected at one end to saidline lter and at the other end tothe free end of a secondary coil of said transformer, a shaping networkconnected in series with said conductor intermediate said ilter and saidsecondary coil.

PAUL J. HOWE. ROBERT T. HAMLET'I. MAURICE A. RUDD.

